US4551989A - Oil equalization system for refrigeration compressors - Google Patents
Oil equalization system for refrigeration compressors Download PDFInfo
- Publication number
- US4551989A US4551989A US06/676,919 US67691984A US4551989A US 4551989 A US4551989 A US 4551989A US 67691984 A US67691984 A US 67691984A US 4551989 A US4551989 A US 4551989A
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- US
- United States
- Prior art keywords
- compressor
- suction
- compressors
- lubricant
- header
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
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Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B31/00—Compressor arrangements
- F25B31/002—Lubrication
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
- F04B39/00—Component parts, details, or accessories, of pumps or pumping systems specially adapted for elastic fluids, not otherwise provided for in, or of interest apart from, groups F04B25/00 - F04B37/00
- F04B39/02—Lubrication
- F04B39/0223—Lubrication characterised by the compressor type
- F04B39/023—Hermetic compressors
- F04B39/0238—Hermetic compressors with oil distribution channels
- F04B39/0246—Hermetic compressors with oil distribution channels in the rotating shaft
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B2400/00—General features or devices for refrigeration machines, plants or systems, combined heating and refrigeration systems or heat-pump systems, i.e. not limited to a particular subgroup of F25B
- F25B2400/07—Details of compressors or related parts
- F25B2400/075—Details of compressors or related parts with parallel compressors
Definitions
- This invention relates to refrigeration systems employing multiple compressors in parallel and particularly to a system for achieving the proper level of lubricant in each of the compressors of such a system when all of the compressors are operating and also when one or more of the compressors are out of operation or operating at partial capacity.
- compressor lubricant During operation of refrigeration compressor systems, it is common for compressor lubricant to be carried from the compressors by the compressed refrigerant, so that, unless it is separated at some point, the lubricant circulates with the refrigerant throughout the system. Where a refrigeration system employs multiple compressors in parallel, it is important that the appropriate amount of lubricant be returned to each of the compressors in order that each compressor has at all times a supply sufficient for its lubrication needs, but not so much lubricant as to impair its operation.
- Another object of the present invention is to provide an improved lubricant return system which avoids complicated and intricate controls to regulate the level of lubricant in parallel refrigeration compressors.
- Another object of the present invention is to provide an improved lubricant return system for parallel refrigeration compressors which avoids excessive buildup of lubricant in compressors of the system which are not operating or which are operating at partial capacity.
- a multiple parallel compressor-type refrigeration system is provided with a suction gas distribution system which apportions lubricant between the compressors of the system in a fashion which maintains the appropriate level of lubricant for operation in each of the compressors.
- the suction gas distribution system of the present invention the desired level of lubricant can be maintained in the compressors of a refrigeration system without resort to any of the devices previously employed for that purpose, such as lubricant equalizing lines between the crankcases of the compressors, separators on the compressor discharges to remove entrained lubricant from the compressor discharge gas, and/or valving and controls to regulate the flow of lubricant between the compressor crankcases or between lubricant separators and the compressors.
- the piping arrangement of the present invention calls for the placement of a common suction header for the parallel compressors at a level which is below the suction inlets for each of the compressors and for the compressors to be connected to the common suction header with branch lines which extend upwardly from the suction header.
- the compressor suction inlets should be at an elevation above the maximum operating level for lubricant in the compressor crankcase.
- the branch suction lines of the system are sized to provide a refrigerant mass velocity, which is sufficiently high to carry lubricant from the common suction header to the compressor suction inlet as an entrained liquid, even at the lowest flow rate condition postulated for a compressor.
- branch lines extending from the common suction header should do so in a symmetrical fashion and with the length of the branch lines being substantially equal. Further, it is preferred that the flow paths to each of the compressors in a system employing the present invention should be able to be drawn from the evaporator discharge without passing the branch connection for any other compressor. Symmetrical suction line branching of the type described is readily accomplished for two compressor systems when a T connection is used to split the flow from the evaporator discharge line to the branch lines connected to the compressor suction inlets.
- Three or more compressors may be piped according to the invention in pyramidal or yoke-type arrangements where the flow from the evaporator outlet is T-split as afore-described into a first suction header and then the flow from each end of the first suction header is again T-split to a second suction header with the lines to the second header from the first suction header being located on the second suction header between three branch lines which either extend to three parallel compressors in the fashion afore-described or to a third suction header which in turn is branched in a similar fashion for a greater number of compressors.
- the pyramidal suction piping of X parallel compressors requires X-1 flow splitting suction headers.
- FIG. 1 is a partial schematic, partial elevational view of a two-compressor parallel refrigeration compressor system utilizing the lubricant return system of the present invention.
- FIG. 1 is an elevational view only with regard to the relationship of the common suction header, compressor suction branch lines and the compressor.
- FIG. 2 is a schematic, partial elevational view of a three compressor parallel refrigeration compressor system utilizing the lubricant return system of the present invention.
- FIG. 2 is an elevational view only with regard to the relationship of the common suction header, compressor suction branch lines and the compressor.
- FIG. 1 a refrigeration system employing a pair of compressors operating in parallel to feed a condenser and evaporator.
- the refrigeration system employs the lubricant distribution and equalization scheme of the present invention and is shown as applied to a system utilizing a pair of reciprocating compressor units depicted generally as units 10 and 20.
- Compressors 10 and 20 are connected in parallel to discharge header 40 which in turn is connected to a condenser unit generally depicted at 50.
- Downstream of condenser 50 is refrigerant throttling means 60 and refrigerant evaporator 70.
- FIG. 1 is schematic with regard to the orientation and relative elevations of discharge header 40, condenser 50, throttling means 60, refrigerant evaporator 70 and outlet line 80: it should be recognized that these components of the system may be located either above or below the plane of the compressors 10 and 20.
- the suction gas enters compressors 10 and 20 through compressor suction inlets 11 and 21 which are located at the top of their respective compressor casings.
- Compressed gas is discharged from compressors 10 and 20 at discharge ports 12 and 22 from whence the compressed gas flows through individual discharge lines to common discharge header 40.
- Lubricant separates from the suction gas in suction chambers at the ends of the compressor casings and accumulates in the bottom of motor chambers 13 and 14 from whence it passes into the lower portion of compressor crankcases 14 and 24, filling crankcases 14 and 24 with lubricant to a level appropriate for the particular compressor model utilized in the refrigeration system.
- the normal levels L 1 and L 2 of accumulated lubricant in crankcases 14 and 24 are at the elevation of sight glasses 15 and 25, which are always below the compressor suction inlets 11 and 21.
- compressors 10 and 20 are depicted in the figure as reciprocating compressors, they may be any other type of compressor which is suitable for use in refrigeration systems.
- evaporator outlet line 80 extends from evaporator 70 in a downward run to suction T 81 which is located at an elevation below compressor suction inlets 11 and 21.
- Branch suction lines 82a and 82b extend from suction T 81 to compressor suction inlets 11 and 21.
- Branch suction lines 82a and 82b are approximately equal in length and are each sized so as to provide for a gas velocity therethrough which is sufficient for lubricant entrainment at the lowest flow rate conditions under which compressors 10 and 20 can operate.
- suction T 81 is located at an elevation relative to suction inlets 11 and 21 such that, at the design gas velocity, lubricant will stay entrained in the suction gas over the vertical run provided therebetween.
- the method for calculating the appropriate lines sizes to achieve lubricant entrainment in the suction gas at design gas flow rates will be familiar to those skilled in the refrigeration art or knowledgeable of the ASHRAE guidelines.
- compressors 10 and 20 pass high-pressure, high-temperature vapor refrigerant with entrained lubricant through discharge ports 12 and 22, into and through the individual discharge lines connected thereto which then merge into discharge header 40.
- the high-temperature refrigerant vapor is cooled, condensed and collected in condenser 50.
- the liquified refrigerant is throttled across regulating valve 60 into evaporator 70 where it absorbs heat from the environment to be refrigerated and rises in temperature to a pre-determined level of superheat.
- suction T 81 the hot refrigerant from evaporator 70 is split into two separate streams which are directed one to compressor 10 and the other to compressor 20.
- suction T 81 and the aligned horizontal sections of branch suction lines 82a and 82b comprises a substantially horizontal common suction header.
- FIG. 2 Shown in FIG. 2 is a multiple parallel compressor-type refrigeration system employing three compressors in parallel.
- the compressors of the system numbered 10, 20 and 30 in the figure, are shown in schematic form as are the condenser 50, throttling means 60 and evaporator 70.
- compressors 10, 20 and 30 are connected in parallel to discharge header 40, which is in turn connected in series to condenser unit 50, refrigerant throttling means 60, and refrigerant evaporator 70.
- Superheated refrigerant vapor from evaporator 70 flows into evaporator outlet line 80 which in turn feeds a pyramidal distribution system.
- the superheated refrigerant vapor in evaporator outlet line 80 flows into suction T 81 which splits the superheated refrigerant between branch suction lines 82a and 82b.
- Branch suction lines 82a and 82b terminate respectively in a common suction header 84 with, respectively, T's 83a and 83b.
- suction header 84 is substantially horizontal.
- T's 83a and 83b are positioned on common suction header 84 at points which are preferably midway between the connection points of branch suction lines 85a, 85b and 85c, which carry the superheated refrigerant vapor to the compressor suction inlets which are depicted in the drawing as respectively 11, 21 and 31.
- Suction header 84 is located at an elevation below compressor suction inlets 11, 21 and 31 and branch suction lines 85a, 85b and 85c are preferably of approximately equal length.
- the branch suction lines are each sized so as to provide for a gas velocity therethrough which is above the minimums specified in connection with the two-compressor system aforedescribed.
- the lubricant return system serves to distribute entrained lubricant between the operating compressors of the system in the same fashion aforedescribed with regard to the two-compressor system depicted in FIG. 1. Accordingly, as superheated suction gas is drawn from suction header 84, according to the requirements of the operating compressors, it will carry with it as an entrained liquid the appropriate amount of lubricant for the maintenance of the proper lubricant level in the manifolds 12, 22 and 32.
- the lubricant return system described herein does not require the use of complicated valving or pumps to maintain the appropriate distribution of lubricant between the compressors of a multiple parallel compressor refrigeration system. Rather, the lubricant return scheme described in simple, inherently reliable and low in cost.
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- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Thermal Sciences (AREA)
- Compressors, Vaccum Pumps And Other Relevant Systems (AREA)
Abstract
Description
Claims (9)
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US06/676,919 US4551989A (en) | 1984-11-30 | 1984-11-30 | Oil equalization system for refrigeration compressors |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US06/676,919 US4551989A (en) | 1984-11-30 | 1984-11-30 | Oil equalization system for refrigeration compressors |
Publications (1)
Publication Number | Publication Date |
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US4551989A true US4551989A (en) | 1985-11-12 |
Family
ID=24716564
Family Applications (1)
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US06/676,919 Expired - Lifetime US4551989A (en) | 1984-11-30 | 1984-11-30 | Oil equalization system for refrigeration compressors |
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Cited By (13)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4750337A (en) * | 1987-10-13 | 1988-06-14 | American Standard Inc. | Oil management in a parallel compressor arrangement |
US4758138A (en) * | 1985-06-07 | 1988-07-19 | Svenska Rotor Maskiner Ab | Oil-free rotary gas compressor with injection of vaporizable liquid |
US5150586A (en) * | 1989-11-16 | 1992-09-29 | Basseggio Narcizo O | System and process of compressing miscible fluids |
US5435144A (en) * | 1994-02-24 | 1995-07-25 | Kalmbach; John | Compressor lubricant distributing system for motor vehicles having auxiliary air conditioning |
US6474405B1 (en) * | 2000-09-26 | 2002-11-05 | Meritor Heavy Vehicle Technology, Llc | Refrigeration utilized to cool driveline lubricants |
US20110120154A1 (en) * | 2008-05-07 | 2011-05-26 | United Technologies Corporation | Passive oil level limiter |
US20140037484A1 (en) * | 2012-07-31 | 2014-02-06 | Bitzer Kuehlmaschinenbau Gmbh | Oil Equalization Configuration for Multiple Compressor Systems Containing Three or More Compressors |
US20140154105A1 (en) * | 2012-12-03 | 2014-06-05 | Danfoss (Tianjin) Ltd. | Oil balancing apparatus and refrigeration device |
US9939179B2 (en) | 2015-12-08 | 2018-04-10 | Bitzer Kuehlmaschinenbau Gmbh | Cascading oil distribution system |
US10760831B2 (en) | 2016-01-22 | 2020-09-01 | Bitzer Kuehlmaschinenbau Gmbh | Oil distribution in multiple-compressor systems utilizing variable speed |
US11274862B2 (en) | 2017-03-21 | 2022-03-15 | Lennox Industries Inc. | Method and apparatus for balanced fluid distribution in multi-compressor systems |
US11415347B2 (en) | 2017-03-21 | 2022-08-16 | Lennox Industries Inc. | Method and apparatus for balanced fluid distribution in tandem-compressor systems |
US11555495B2 (en) * | 2020-02-04 | 2023-01-17 | Carrier Corporation | Fluid equalisation for multiple compressors |
Citations (16)
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---|---|---|---|---|
US3360958A (en) * | 1966-01-21 | 1968-01-02 | Trane Co | Multiple compressor lubrication apparatus |
US3386262A (en) * | 1966-10-31 | 1968-06-04 | Trane Co | Refrigeration apparatus with compressors in parallel |
US3503223A (en) * | 1968-07-29 | 1970-03-31 | Lennox Ind Inc | Refrigeration system having tandem compressor arrangement |
US3580006A (en) * | 1969-04-14 | 1971-05-25 | Lester K Quick | Central refrigeration system with automatic standby compressor capacity |
US3581519A (en) * | 1969-07-18 | 1971-06-01 | Emhart Corp | Oil equalization system |
US3621670A (en) * | 1970-01-12 | 1971-11-23 | Vilter Manufacturing Corp | Lubricating oil equalizing system |
US3633377A (en) * | 1969-04-11 | 1972-01-11 | Lester K Quick | Refrigeration system oil separator |
US3645109A (en) * | 1970-03-16 | 1972-02-29 | Lester K Quick | Refrigeration system with hot gas defrosting |
US3719057A (en) * | 1971-10-08 | 1973-03-06 | Vilter Manufacturing Corp | Two-stage refrigeration system having crankcase pressure regulation in high stage compressor |
US3785169A (en) * | 1972-06-19 | 1974-01-15 | Westinghouse Electric Corp | Multiple compressor refrigeration system |
US3905202A (en) * | 1974-01-08 | 1975-09-16 | Emhart Corp | Refrigeration system |
US4053725A (en) * | 1976-04-07 | 1977-10-11 | Kramer Daniel E | Pressure switch for outdoor refrigeration systems |
US4102149A (en) * | 1977-04-22 | 1978-07-25 | Westinghouse Electric Corp. | Variable capacity multiple compressor refrigeration system |
US4179248A (en) * | 1978-08-02 | 1979-12-18 | Dunham-Bush, Inc. | Oil equalization system for parallel connected hermetic helical screw compressor units |
US4383802A (en) * | 1981-07-06 | 1983-05-17 | Dunham-Bush, Inc. | Oil equalization system for parallel connected compressors |
US4411141A (en) * | 1981-02-06 | 1983-10-25 | Mitsubishi Denki Kabushiki Kaisha | Parallel operation compressor type refrigerating apparatus |
-
1984
- 1984-11-30 US US06/676,919 patent/US4551989A/en not_active Expired - Lifetime
Patent Citations (16)
Publication number | Priority date | Publication date | Assignee | Title |
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US3360958A (en) * | 1966-01-21 | 1968-01-02 | Trane Co | Multiple compressor lubrication apparatus |
US3386262A (en) * | 1966-10-31 | 1968-06-04 | Trane Co | Refrigeration apparatus with compressors in parallel |
US3503223A (en) * | 1968-07-29 | 1970-03-31 | Lennox Ind Inc | Refrigeration system having tandem compressor arrangement |
US3633377A (en) * | 1969-04-11 | 1972-01-11 | Lester K Quick | Refrigeration system oil separator |
US3580006A (en) * | 1969-04-14 | 1971-05-25 | Lester K Quick | Central refrigeration system with automatic standby compressor capacity |
US3581519A (en) * | 1969-07-18 | 1971-06-01 | Emhart Corp | Oil equalization system |
US3621670A (en) * | 1970-01-12 | 1971-11-23 | Vilter Manufacturing Corp | Lubricating oil equalizing system |
US3645109A (en) * | 1970-03-16 | 1972-02-29 | Lester K Quick | Refrigeration system with hot gas defrosting |
US3719057A (en) * | 1971-10-08 | 1973-03-06 | Vilter Manufacturing Corp | Two-stage refrigeration system having crankcase pressure regulation in high stage compressor |
US3785169A (en) * | 1972-06-19 | 1974-01-15 | Westinghouse Electric Corp | Multiple compressor refrigeration system |
US3905202A (en) * | 1974-01-08 | 1975-09-16 | Emhart Corp | Refrigeration system |
US4053725A (en) * | 1976-04-07 | 1977-10-11 | Kramer Daniel E | Pressure switch for outdoor refrigeration systems |
US4102149A (en) * | 1977-04-22 | 1978-07-25 | Westinghouse Electric Corp. | Variable capacity multiple compressor refrigeration system |
US4179248A (en) * | 1978-08-02 | 1979-12-18 | Dunham-Bush, Inc. | Oil equalization system for parallel connected hermetic helical screw compressor units |
US4411141A (en) * | 1981-02-06 | 1983-10-25 | Mitsubishi Denki Kabushiki Kaisha | Parallel operation compressor type refrigerating apparatus |
US4383802A (en) * | 1981-07-06 | 1983-05-17 | Dunham-Bush, Inc. | Oil equalization system for parallel connected compressors |
Cited By (18)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4758138A (en) * | 1985-06-07 | 1988-07-19 | Svenska Rotor Maskiner Ab | Oil-free rotary gas compressor with injection of vaporizable liquid |
US4750337A (en) * | 1987-10-13 | 1988-06-14 | American Standard Inc. | Oil management in a parallel compressor arrangement |
US5150586A (en) * | 1989-11-16 | 1992-09-29 | Basseggio Narcizo O | System and process of compressing miscible fluids |
US5435144A (en) * | 1994-02-24 | 1995-07-25 | Kalmbach; John | Compressor lubricant distributing system for motor vehicles having auxiliary air conditioning |
US6474405B1 (en) * | 2000-09-26 | 2002-11-05 | Meritor Heavy Vehicle Technology, Llc | Refrigeration utilized to cool driveline lubricants |
US20110120154A1 (en) * | 2008-05-07 | 2011-05-26 | United Technologies Corporation | Passive oil level limiter |
US9541312B2 (en) * | 2008-05-07 | 2017-01-10 | United Technologies Corporation | Passive oil level limiter |
CN104619988A (en) * | 2012-07-31 | 2015-05-13 | 比策尔制冷机械制造有限公司 | Oil equalization configuration for multiple compressor systems containing three or more compressors |
US20140037484A1 (en) * | 2012-07-31 | 2014-02-06 | Bitzer Kuehlmaschinenbau Gmbh | Oil Equalization Configuration for Multiple Compressor Systems Containing Three or More Compressors |
US10495089B2 (en) * | 2012-07-31 | 2019-12-03 | Bitzer Kuehlmashinenbau GmbH | Oil equalization configuration for multiple compressor systems containing three or more compressors |
US10612549B2 (en) | 2012-07-31 | 2020-04-07 | Bitzer Kuehlmaschinenbau Gmbh | Oil equalization configuration for multiple compressor systems containing three or more compressors |
US20140154105A1 (en) * | 2012-12-03 | 2014-06-05 | Danfoss (Tianjin) Ltd. | Oil balancing apparatus and refrigeration device |
US9657975B2 (en) * | 2012-12-03 | 2017-05-23 | Danfoss (Tianjin) Ltd. | Oil balancing apparatus and refrigeration device |
US9939179B2 (en) | 2015-12-08 | 2018-04-10 | Bitzer Kuehlmaschinenbau Gmbh | Cascading oil distribution system |
US10760831B2 (en) | 2016-01-22 | 2020-09-01 | Bitzer Kuehlmaschinenbau Gmbh | Oil distribution in multiple-compressor systems utilizing variable speed |
US11274862B2 (en) | 2017-03-21 | 2022-03-15 | Lennox Industries Inc. | Method and apparatus for balanced fluid distribution in multi-compressor systems |
US11415347B2 (en) | 2017-03-21 | 2022-08-16 | Lennox Industries Inc. | Method and apparatus for balanced fluid distribution in tandem-compressor systems |
US11555495B2 (en) * | 2020-02-04 | 2023-01-17 | Carrier Corporation | Fluid equalisation for multiple compressors |
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